The present project represents the first high-risk study of Attention Deficit Hyperactivity Disorder (ADHD). Its overall aim is to advance our understanding of the familial pattern of ADHD, using a high-risk design that examines risks conferred to offspring of individuals who had ADHD in childhood. Specifically, we will examine in children at high and low risk for ADHD: (1) differential social, behavioral, cognitive, and diagnostic characteristics, and; (2) differential risk factors, including familial features and parental psychopathology. The findings of this study will provide information critical to the identification of vulnerable and at risk children and will contribute to the rational design of preventive approaches.